1. Field of the Invention
The invention relates in general to a light guide device, and more particularly to an edge-lit light guide device and an illumination device using the same thereof.
2. Description of the Related Art
Currently, the issue of light-emitting efficiency needs to be resolved so that conventional T5/T8 fluorescent lamps can be replaced with shorter edge-lit LED light guide bars.
Referring to FIG. 1A, a schematic diagram of a generally known edge-lit LED illumination device 1-1 is shown. As indicated in FIG. 1A, the illumination device 1-1 comprises a light source 12 and a light guide bar 102. The light source 12 is disposed at the outside of an end surface 1021 of the light guide bar 102. When a light beam L11 of the light source 12 enters the light guide bar 102, at least ±2° of the light will be leaked through another end surface 1022 of the light guide bar 102 and cannot be emitted out from the light-emitting surface 1023a of the light guide bar 102. Consequently, the light-emitting efficiency of the illumination device 1-1 is poor.
Referring to FIG. 1B, a schematic diagram of a generally known edge-lit LED illumination device 1-2 is shown. The illumination device 1-2 of FIG. 1B comprises a light source 12 and a light guide bar 102. The light source 12 of FIG. 1B is the same with the light guide bar 102 and FIG. 1A, and the similarities are not repeated here. It is noted that a reflective planar plate P is disposed on another end surface 1022 of the light guide bar 102 of the illumination device 1-2. When the light beam L13 of the light source 12 proceeds to the underneath of the reflective planar plate P via the inside of the light guide bar 102, the light beam L13 is reflected to the light-emitting surface by the reflective plate P and then is emitted to the outside from the light-emitting surface. Thus, the light beam will not be leaked via another end surface 1022 of the light guide bar 102. However, when the light beam L12 of the light source 12 proceeds to the top of the reflective planar plate P via the inside of the light guide bar 102, the light beam L12 is reflected to the end surface 1021 by the reflective planar plate P and light leakage will occur. The light guide device of the illumination device 1-2 still cannot effectively resolve the problem of light leakage, and the issue of light-emitting efficiency still has plenty of room to improve.